The invention relates to a method and an apparatus for performing the method of separating contaminants of various types present in fibrous suspensions. The invention particularly relates to fibrous suspensions common in the production of paper and of cellulose or the like. In the separation apparatus, the fluid is admitted into a housing in which a rotor generates a potential vortex in such a way that lightweight contaminants accumulate in a wall region generally opposite the rotor while the relatively heavy contaminants migrate radially outward and are eliminated from the housing while the cleaned suspension traverses a sieve and is also removed from the housing.
A method and an apparatus for performing this method has been described in U.S. Pat. No. 3,844,488. The main area of use of this method and apparatus is in the preparation of recycled paper. A rotor creates a potential vortex which separates the contaminants of relatively low and high weight. The lightweight contaminants travel in the core of the vortex and are removed through an opening located opposite the rotor on its own axis. The heavier contaminants are removed at the circumference of the container. One major disadvantage of the known apparatus described above is that the sieve surface which is effective for the flow of fluid is small and thus presents upper limits for the throughput. Furthermore, the wear and tear on the rotor, the sieve or screen, as well as the container itself, is high because the fluid flow within the housing as well as the removal of heavy contaminants do not take place in an optimum manner. The continuous rollover motion of the heavy contaminants in particular causes those contaminants to contact the rotor and the screen often with the result of causing substantial wear and tear in these parts.